Machining

Machining removes material with cutting tools or abrasives to produce accurate parts with good finishes across metals and plastics, from prototypes to production.

Overview

Machining is a subtractive manufacturing category that shapes parts by removing material using cutting tools or abrasives. It covers milling (prismatic features, pockets, contours), turning (cylindrical features), drilling (holes), grinding (tight size/finish), EDM (hard materials and sharp internal features), and broaching (fast, repeatable internal profiles like splines).

Choose machining when you need controlled dimensions, predictable material properties, and clean functional surfaces—especially for low to medium volumes, prototypes, fixtures, and critical interfaces. It supports a wide range of materials and can hit tight tolerances with minimal process risk.

Tradeoffs: cost scales with cycle time, setups, and workholding complexity; deep cavities, small tools, and multiple orientations drive price. Internal sharp corners are limited by tool radius (except EDM/broaching), and burr control or secondary deburring may be required.

Common Materials

  • Aluminum 6061
  • Stainless 304
  • Steel 1018
  • Titanium Grade 5
  • Brass C360
  • POM (Delrin)

Tolerances

±0.001" to ±0.005"

Applications

  • Precision shafts and spacers
  • Valve bodies and manifolds
  • Bearing housings
  • Custom fixtures and nests
  • Gear blanks and splined hubs
  • Prototype brackets and enclosures

When to Choose Machining

Machining fits parts that need accurate datums, controlled bores, flatness, and reliable material properties. It’s a strong choice for prototypes through medium-volume production where design changes are likely or inventory risk is high. It also works well when surfaces are functional (seals, bearings, threads) and must be produced to print without shrink or porosity concerns.

vs 3D printing (additive manufacturing)

Choose machining when you need tighter tolerances, better surface finish on functional interfaces, or production-grade wrought materials. It’s also preferred when post-processing additive parts would erase the lead-time or cost advantage.

vs Injection molding

Choose machining when volumes are low to medium, the design may change, or you can’t justify tooling lead time and cost. Machining also supports thicker sections and a wider range of engineering materials without moldability constraints.

vs Sheet metal fabrication

Choose machining when the part needs true 3D geometry, precise bores, sealing surfaces, or rigid features not achievable from bends and fasteners. It’s also better for thick stock and tight positional tolerances between features.

vs Casting

Choose machining when you need fully dense material, faster iteration, or tighter control of critical dimensions without relying on secondary machining of many features. Machining is also cleaner for low quantities where pattern/tooling cost dominates.

vs Laser/waterjet cutting

Choose machining when you need 3D features (pockets, steps, threads), controlled depth, or tight perpendicularity and finish on critical edges. Cutting is typically limited to 2D profiles and may leave taper or edge condition that still requires machining.

Design Considerations

  • Define clear datums and inspectable tolerances; avoid over-tolerancing non-critical features
  • Ensure tool access by keeping cavity depths reasonable and avoiding unreachable internal features
  • Use standard hole sizes and thread series; call out class/fit only where needed
  • Add internal corner radii that match common endmill sizes; avoid sharp internal corners unless you plan for EDM/broaching
  • Minimize setups by aligning critical features to common orientations and limiting features that require multiple re-clamps
  • Call out surface finish only on functional surfaces; default roughness elsewhere to reduce cycle time